at89c51snd1 ATMEL Corporation, at89c51snd1 Datasheet - Page 20

• Manufacturer Part Number: at89c51snd1
• Description: Mp3 Microcontrollers
• Manufacturer: ATMEL Corporation

In-Application
Programming/Self-
Programming
API Call
Process
Constraints
API Commands
Read/Program Flash Memory
20
AT89C51SND1 UART Bootloader
The IAP allows to reprogram the microcontroller’s on-chip Flash memory without remov-
ing it from the system and while the embedded application is running.
The user application can call some Application Programming Interface (API) routines
allowing IAP. These API are executed by the bootloader.
To call the corresponding API, the user must use a set of Flash_api routines which can
be linked with the application.
Example of Flash_api routines are available on the Atmel web site on the software appli-
cation note:
The flash_api routines on the package work only with the UART bootloader.
The flash_api routines are listed in APPENDIX B.
The application selects an API by setting R1, ACC, DPTR0 and DPTR1 registers.
All calls are made through a common interface “USER_CALL” at the address FFF0h.
The jump at the USER_CALL must be done by LCALL instruction to be able to come-
back in the application.
Before jump at the USER_CALL, the bit ENBOOT in AUXR1 register must be set.
The interrupts are not disabled by the bootloader.
Interrupts must be disabled by user prior to jump to the USER_CALL, then re-enabled
when returning.
The user must take care of hardware watchdog before launching a Flash operation.
For more information regarding the Flash writing time refer to the AT89C51SND1
datasheet.
Several types of APIs are available:
•
•
•
•
•
All routines to access Flash data are managed directly from the application without
using bootloader resources.
To read the Flash memory the bootloader is not involved.
For more details on these routines see the AT89C51SND1 Datasheet sections “Pro-
gram/Code Memory”.
Two routines are available to program the Flash:
–
Read/Program Flash Data memory
Read Configuration and Manufacturer Information
Program Configuration Information
Erase Flash
Start bootloader
–
–
C Flash Drivers for the AT89C51SND1.
__api_wr_code_byte
__api_wr_code_page
4241B–MP3–07/04